1. Field of the Invention
The present invention relates to automotive warning systems, and more particularly to a microprocessor-based visual warning system that accounts for variations in vehicular speed and other factors in providing a variable warning signal to trailing vehicles.
2. Description of the Related Art
Drivers of automobiles have two main methods of communicating their presence and intentions to one another--by visual means such as lights and by audible means such as a horn The horn allows a driver to communicate with other drivers and pedestrians who may not be in visual contact. Lights allow drivers to visually inform others of their presence and intentions.
Automobiles typically incorporate a variety of lights, with most operating in pairs. Pairs of lights used to send specific information or perform other functions are customarily placed at the front, back and sides of an automobile. For example, pairs of turning lights can be activated prior to a change in direction. Pairs of emergency flashing lights are used to apprise others of hazardous conditions or as a distress signal. Headlights with low and high beams are used primarily to allow the driver to see and be seen at night. Finally, a pair of brake lights and a pair of back-up warning lights are conventionally placed at the back of automobiles to inform following drivers of braking and backing activities. Generally, the brake lights are simply illuminated when pressure is applied to the automobile's brake pedal--the brake lights do not provide any information regarding the magnitude of speed reductions with respect to the automobile's speed and ambient driving conditions.
The standard pairs of lights described above can be divided in two groups depending on how they are operated.
The first group includes lights actively operated by the driver with the sole and full intention of sending specific information to other drivers or when a particular driving environment renders their usage inevitable. This group is comprised of turn signal lights, emergency flashing lights, parking lights and headlights.
A second group includes those lights that are passively activated or operated by the driver. These lights are switched on and off automatically in response to particular vehicular operations. Brake lights (including any center-mounted rear brake lights) and back-up warning lights are included in this second group of lights. Passive lights are capable of providing limited information simultaneous with the occurrence of specified operations.
There are known prior art warning light systems that suggest varying the intensity or frequency of blinking rate in response to a variable such as the magnitude of deceleration brought about by braking operations. For example, U.S. Pat. No. 3,760,353 to Blomenkamp et al. describes a signal light that flashes after a predetermined level of deceleration is measured. Similarly, U.S. Pat. No. 4,355,594 to Ehrlich et al. describes a hazard warning indicator that is energized to a magnitude that is proportional to the degree of deceleration of a vehicle or other measurement such as brake pressure; U.S. Pat. No. 5,481,243 to Lurie et al. dual audio and visual indicators that depend on differential vehicular deceleration measurements; U.S. Pat. No. 4,952,909 to Woerner et al. an early warning system for anticipating vehicle braking by monitoring depression of the vehicle's accelerator; and U.S. Pat. No. 5,231,373 a signal light source with an intensity level that varies as a function of at least one safety-affecting parameter and a time-varying function compensating for physiological inability to perceive certain changes in intensity levels.
These systems suffer from major shortcomings. For instance, the intensity or frequency of warning signals is the same for a given rate of deceleration, regardless of a vehicle's actual speed. In addition, these systems largely ignore ambient driving conditions in calculating the intensity of a warning signal.